ISLAMABAD: In a good omen to crop output in both current and next cropping season, the country’s two major reservoirs — Tarbela and Mangla — are now almost full to capacity, turning into surplus the acute water shortage that marked beginning of the current Kharif season in April.

The total storage in two dams is now above 13.1 million acre feet (MAF), only a few thousand feet below the maximum conservation capacity and that too mostly because of operational and precautionary reasons to keep some space for unexpected flash flows amid rain and thunderstorm forecasts.

“There is no shortage at all, except maybe somewhere because of carrying constraints in the irrigation system like canal limitations at the tail-end in provinces; rather we have surplus water in the system and more rains are still expected”, confirmed Khalid Idrees Rana, the spokesperson for the Indus River System Authority (Irsa) hoping that more than 10MAF water would be carried forward to the Rabi cropping season in October after a gap of a couple of years. That would be good sign for Rabi crops after many years.

In may be recalled that Kharif season had started in April with 37pc anticipated water shortage with 27pc shortage in early Kharif and about 10pc in late Kharif. There will be no shortage in the late Kharif. The regulator and the provinces have managed early Kharif well in view of feared shortages.

In fact, Tarbela dam had attained its maximum elevation of 1550feet or 5.8MAF storage last week but was slightly reduced by the authorities by diverting about 15,000 cusec through Chashma-Jhelum and Taunsa-Punjnad canals to Punjab’s irrigation mainland that is usually served through Mangla dam.

This, too, is for precautionary measure to contain flash flows as weather pundits have predicted ‘moderate to heavy’ rainfalls over the next few days. Still, conservation level at Tarbela remains at 1549.05 feet or 5.754MAF of storage. Flows in the Chenab are also expected to remain favourable to support Jhelum-Chenab canal command areas.

Luckily, Eastern rivers — Ravi, Beas and Sutlej — flowed with sufficient waters after a gap of more than a decade and enough water is available in system downstream of these rivers, reducing the need for discharges from Mangla dam. This mega dam on the Jhelum is now standing at 1240 feet elevation, just two feet below its 1242 feet peak and has attained such a situation after a gap of 3-4 years. Its storage now stands at 7.18MAF against its peak capacity of 7.35MAF. With continuous diversion from Indus Zone to Jhelum-Chenab Zone, Mangla dam is expected to be filled to capacity no about 5-6 days.

The flows in Eastern rivers are also a sign of climate change that weather and flow patterns have differed after a gap of 10-15 years, giving a warning to the people in the downstream to keep safe distances from old river beds.

Besides medium to heavy rainfalls predicted by Pakistan Meteorological Department (PMD) in the catchments of Tarbela, temperatures in snowy peaks of Skardu are favourable at above 31 degree Celsius which means river flows would go beyond 250,000 cusec from about 227,000 cusec at present. As a result, the authorities would have increase outflows from Tarbela to run-of-the-river position — all inflows going downstream.

With more than 13MAF storage in dams by end of current month, the only water requirement for current crops would be around 2.5MAF for the final watering in the last leg of September, leaving a healthy carryover storage of about 10.5-10.7MAF for the next Rabi season beginning October 1, 2023. Normally, Rabi seldom starts with carryover storage of 8MAF.

On top of this, Indian reservoirs on Sutlej nad Beas are now again nearing maximum levels with just 6 feet and 4 feet left in Bhakra and Pong storages. Given the predicted weather conditions of moderate to heavy rainfalls in upper catchments of Sutlej and Beas, India would have to let flows into Pakistan in a few days.

At present, total inflows at the rim stations were recorded at 377,000 cusec on August 14 against total outflows of about 357,000cusec. Discharges from Tarbela dam are greater than inflows at present compared to Mangla dam outflows have been kept at just 10,000 cusec at present compared to about 30,000 cusec inflows. As of now, about 7.34 MAF water has flowed downstream Kotri barrage since the start of current Kharif season on April 1.

There are two principal crop seasons in Pakistan, namely the Kharif, in which sowing begins in April and harvesting in October while and the Rabi, begins in October and lasts till April. Rice, sugarcane, cotton, maize, mong, mash, bajra and jowar are Kharif crops while wheat, gram, lentil (masoor), tobacco, rapeseed, barley and mustard are Rabi crops.

Published in Dawn, August 15th, 2023